President Obama will travel to Newtown, Conn., on Sunday to meet with the families of the the 26 people who were slain at Sandy Hook Elementary School, the White House said today.

The president, who will also meet with first responders, is scheduled to speak at an interfaith service in Newtown at 7 p.m., according to a statement from the Office of the Press Secretary.

One day after Obama addressed the nation, mourning the children who "had their entire lives ahead of them -- birthdays, graduations, weddings, kids of their own," the world learned just how grim the scene inside Sandy Hook was.

The gunman massacred 20 first graders, shooting some of them as many as 11 times, the medical examiner said today.

"I've been at this for a third of a century so my sensibilities may not be the that of the average man, but it's probably the worst I've ever seen," said Chief Medical Examiner H. Wayne Carver II, who has been a medical examiner for 36 years.

A team of 14 medical technicians worked through the night to complete the grisly job of identifying the children killed by Adam Lanza, 20, in the Sandy Hook Elementary School massacre so their names could be released today.

"I believe many of them were hit more than once," and he said the wounds were "all over" the children's bodies.

"I only did seven of the autopsies. The victims I had ranged from three to 11 wounds a piece," Carver said.

The names of the children slain Friday in the school were released today.

To carry out the identifications, Carver said they "did not bring the families and the bodies into contact." He said the identifications were made through photographs of the children's faces.

"It's easier on the families," he said.

Additional work is needed to complete the autopsies and identifications of the seven adults slain in Lanza's killing spree.

Fresh details of the massacre emerged, including the fact that all of the young victims were first graders in two rooms.

Based on the Sandy Hook school directory, all the kids killed were in the first grade and were in two classrooms.

In one class, 15 of the 16 students listed were killed. In the other class, five of the 16 students died along with their teacher, Victoria Soto. Also, nine of the deceased students have siblings in the school.

At a nearby firehouse that has become a center for the town, a makeshift memorial and vigil has emerged under a sign that reads "Sandy Hook School." People have left flowers, candles, signs that read "Rest in Peace" and "God Bless Sandy Hook Elementary," as well as a cross made of blue flowers and a wreath of teddy bears

With the tally of Lanza's carnage complete, authorities and the grieving people of Newtown are left to wonder why he turned the elementary school in this quaint New England town into a slaughter house.

Connecticut State Police Lt. Paul Vance said the investigation "did produce some very good evidence" about motive, but he would not go into further detail.

He indicated the evidence came from the shooting scene at the school as well as at the home where Lanza's mother, Nancy, was slain.

Also key will be the lone person shot by Lanza who wasn't killed. The female teacher has not been publicly identified.

"She is doing fine," Vance said at a news conference today. "She has been treated and she'll be instrumental in this investigation."

Vance said it appears that reports of an altercation involving Lanza at the school in the days before the mass slaying are not checking out.

Vance said that Lanza forced his way into the school, but did not say how.

Evidence emerged today that Lanza's rampage began in the office of school principal Dawn Hochsprung while the school intercom was on. It's not clear whether it was turned on to alert the school or whether it was on for morning announcements, but the principal's screams and the cries of children heard throughout the school gave teachers time to take precautions to protect their children.

Hochsprung was among those killed in the Friday morning killing spree.

Authorities have fanned out to New Jersey, Connecticut and Massachusetts to interview Lanza's relatives, ABC News has learned.

According to sources, Lanza shot his mother in the face, then left his house armed with at least two semi-automatic handguns, a Glock and a Sig Sauer, and a semi-automatic rifle. He was also wearing a bulletproof vest.

Newtown Police Hunt for Motive in School Massacre

Lanza then drove to the elementary school to carry out his murderous plan, authorities said.

It appeared that Lanza died from what was believed to be a self-inflicted gunshot wound.

Lanza's father, Peter Lanza, released a statement today saying the family is "grieving along with all those who have been affected by this enormous tragedy."

"No words can truly express how heartbroken we are," he said. "We are in a state of disbelief and trying to find whatever answers we can. We too are asking why. We have cooperated fully with law enforcement and will continue to do so. Like so many of you, we are saddened, but struggling to make sense of what has transpired."

This is the second worst mass shooting in U.S. history, exceeded only by the Virginia Tech shooting in 2007 when 32 were killed before the shooter turned the gun on himself. The carnage in Connecticut exceeded the 1999 Columbine High School shooting in which 13 died and 24 were injured.

Friday's shooting came three days after masked gunman Jacob Roberts opened fire in a busy Oregon mall, killing two before turning the gun on himself.

The Connecticut shooting occurred at the Sandy Hook Elementary School, which includes 450 students in grades K-4. The town is located about 12 miles east of Danbury, Conn.